Electronic displays are commonly used to display computer-generated digital data or video images. They are used in a wide variety of products including, but not limited to, computers, medical instruments, radar systems, and television sets.
Color liquid crystal displays ("LCD's") embody one of the more common display technologies. Color LCD's include a color filter layer commonly made of a transparent glass substrate coated with green, blue and red dots or stripes ("dots") of dye. These dots are grouped in triads of one red, one blue and one green dot, which together correspond to a single pixel. For common displays, such as those used in computer systems the dots measure between 100 and 300 microns in diameter.
These red, green and blue dots are made by printing the colored dyes on the surface of the substrate. There are drawbacks to manufacturing a color filter by a printing process, however. The printing dyes degrade when heated, and LCD displays are relatively hot. The result is that LCD displays typically have a practical lifespan of less than 2000 hours before color changes result. Since the heating is not homogeneous across the display, the color change of individual pixels may become apparent even before this lifespan is reached in some applications. The displays are difficult to create reliably. Printing produces color regions of inconsistent thickness that cause variations in color across the surface of an LCD display. The color layer, even when carefully printed, must be later polished to provide a surface smooth enough to allow necessary electrodes to be formed on its surface. Polishing is not without risk. It can damage or remove the thin color layer from individual display pixels. A few damaged dots may cause an entire color filter to be scrapped. The printing process often fails to print individual dots as well. Since the dyes are applied in a liquid state, dust may be entrained in the printed color regions. These dust particles block light, form voids, and further increase variations in color filter thickness.
All the aforementioned problems make it difficult to create inexpensive color filters for electronic displays.
It is an object of this invention to produce a color filter for electronic displays having a consistent thickness and optical properties. It is a further object of this invention to create a display that can be polished while reducing the risk that the color layer will peel off the transparent substrate. It is a further object of this invention to increase the color filter's capacity to be polished without damage. It is a further object of this invention to allow the production of smaller pixels at reduced cost. It is a further object to create a color filter having a long life.